void main() {
  sayHi();
  eatFoods('北京烤鸭');
  eatFoods('北京烤鸭', food2: '北京炸酱面', drink: '雪碧');
}

sayHi() {
  print("hi");
}

sayHello(String name) {
  print('$name,hello');
}

sum(int a, int b) {
  return a + b;
}

//必选参数 food1
//可选参数 {类型 变量名 = 默认值，类型？变量名}
eatFoods(String food1, {String? food2, String? drink = '可乐'}) {
  print('$food1,$food2,$drink');
}
